Sift a teaspoonful of cream of tartar six times with a half cupful of flour. Whip the whites of six eggs until they stand alone, then gradually stir into them a half cupful of granulated sugar and the sifted flour. Beat hard and turn into a clean ungreased pan with a funnel in the middle. Bake in a steady oven until a straw comes out clean from the thickest part. Turn the pan upside down upon a clean towel and as the cake cools it will slip out of the tin. When it is cold, ice the bottom and sides of the loaf.